For the nucleic acid analysis of, for example, white blood cells from whole blood to answer questions concerning such matters as the human genome, cells must first be broken open in a sample preparation step and the DNA freed in this way must subsequently be isolated. At the same time, constituents of the blood such as for example hemoglobin, immunoglobulins and lactoferrin, which could inhibit a subsequent polymerase chain reaction, must be removed.
These working steps are carried out in a laboratory on the basis of the known prior art. So, apart from other procedures, cells may be broken open with alkaline solution (NaOH) and the DNA subsequently bonded to silica-coated magnetic beads. By applying a magnetic field, the magnetic beads charged with DNA can be securely held and washed. The isolated DNA can subsequently be eluted from the beads or used together with the beads (as a DNA/bead complex) for the PCR.
In DE 10 2004 021822 A1, which is not a prior publication, it is described how magnetic isolation and a polymerase chain reaction are combined in an integrated miniaturized cartridge. In this case, attention is mainly given to the arrangements in the cartridge. It is not disclosed there how the controlling and actuating device must be constructed in order to realize combined microfluidics, bead isolation and thermocycling.